383MAGNUMROADRUNNER

I HAVE A 1969 ROADRUNNER, REBUILT 383 MAG 4 SPEED THAT I JUST FINISHED WORKING ON. I CONVERTED IT TO ELECTRONIC IGNITION. NEW ALTERNATOR, NEW DIST, ELECT IGNITION, DUAL BALLAST RESISTER, AND VOLT REG. IT RAN FINE FOR ABOUT 50 MILES AND THE ENGINE HARNESS MELTED UP AND SHORTED OUT. IT ALSO MELTED WIRES INTO THE DASH HARNESS. I FIXED THE WIRES AND PUT IN A NEW YEAR ONE ENGINE HARNESS. I HOOKED UP THE BATTERY AND THE WIRES SHORTED AT THE ALTERNATOR AND MELTED UP THE ENGINE HARNESS IMMEDIATELY. I HAD THE NEW ALT CHECKED AND IT IS FINE. NOW I HAVE REPLACED A NEW DASH HARNESS AND NEW ENGINE HARNESS BUT AM AFRAID TO CONNECT UP THE BATTERY. IT MUST BE A SEVERE GROUND ISSUE. DOES ANYONE KNOW WHAT MAY BE WRONG BEFORE I CONNECT THE BATTERY AND HAVE THE SAME PROBLEM AGAIN. THANKS TIM. (BURN'T OUT)

440roadrunner

!!YIKES!! I would do the following:

Strip out the engine bay and under--dash harnesses, stretch them out of plywood, and use tags, masking tape, owr whatever is useful to mark things, and "tack" the harness out so that it "lays" stable. Then untape and or cut it open so you can see what and where is melted together.

When you have either replaced or repaired the harnesses to the point where "you think" they "might work" You will kick yourself when you hear how easy it is to protect.


After you get everything (you hope) repaired and re--installed, hook everything up "as per normal" EXCEPT the battery ground.

Now get yourself some sort of lamp socket such as a dome or stoplight socket, install a good bulb, and simply wire that in series with the battery ground.

IF the lamp lights when you hook it up, it means either the short is still present or that something in the car is drawing current.

Pull fuses one by one and see if the lamp goes out.

Unhook the alternator main output wire and tape it off

Then unhook "major" current drawing components, the horn relay, the headlight switch, the ignition switch, just keep unhooking switches and connectors until that lamp goes out.

When you run out of things, or when you find "the one" post back here or shoot me a PM.

NOTE Sometimes in some cases it is "handy" to have DIFFERENT types of lamps for this sort of testing. I usually have on hand the following:

A low beam headlamp, as I can hook up either low or high, or both beams, which gives me a choice of 3 different loads

A stop/ tail lamp socket with an 1157 bulb. Just like the headlight, this gives me 3 choices, tail only, stop only, or stop and tail in parallel for more current.

For very light loads, I use my common 12V test lamp which does not draw very much.

DO YOU have a factory shop manual? If not, post back, I believe there's one you can download.

383MAGNUMROADRUNNER

I HAVE THE WIRING DIAGRAM FOR 1969 AND 1970 ROADRUNNER. I HAVE ALL NEW DASH AND ENGINE WIRE HARNESS ALMOST INSTALLED. THE WIRES THAT MELTED AND BURNT UP WERE THE BLACK GROUND AND BLUE WIRES TO THE IGNITION SWITCH AND THE BLACK WIRE GOING TO THE ALTERNATOR. I WILL CHECK AS YOU SAID WITH TEST LIGHT. NOT ABLE TO GET TO CAR TODAY. THANKS TIM

440roadrunner

The black wire to the alternator is a gigantic clue. I would suspect problems in the alternator, even though (didn't you say?) it tested OK?

I don't believe in a lot of this bench testing. I have always tested components "on the car" but that's another story.

Would you explain what you mean by the "black ground wire?" I dearly hope you are not referring to the alternator wire, as this is NOT a ground.

Since the blue ignition wire burned, that of course would be the second thing I would disconnect after connecting your test lamp.

Turn the key to "run" and disconnect the blue from the ballast resistor AND disconnect the "push on" terminal of your voltage regulator

Are you still using the early style, that is, the original type 69/ earlier voltage regulator?

Do NOT go by the 70 diagram. There are significant differences.

383MAGNUMROADRUNNER

THE BLACK WIRE TO THE BATTERY POST ON THE ALTERNATOR BURNT UP. THE OTHER WIRES THAT BURNT UP WERE THE BLACK (I THINK GROUND WIRE TO THE IGNITION CYLINDER AND THE BLUE WIRE TO THE IGNITION CYLINDER.) THE CENTER TERMINAL ON THE INSIDE OF THE DIST CAP ALSO WAS DAMAGED. I AM REPLACING NEW SPARK PLUG WIRES ALSO. THE VOLTAGE REGULATOR IS THE NEW STYLE. NEW ELECTRONIC IGNITION AND NEW DISTRIBUTOR, ALSO NEW COIL FOR ELECTRONIC IGNITION. EVERYTHING WAS NEW SO IT SHOULD HAVE WORKED FINE.

440roadrunner

Please find your "caps lock" key and turn it off. We are not in the 1960's, and you are not using a teletype machine

Are you ABSOLUTELY sure you did not hook the battery up backwards, or that the battery has become reverse charged? This HAS happened.

I would as I said suspect the alternator. Secondly, suspect the horn relay/ horn circuit. It appears that the horn relay picks power up directly off the alternator, and this is NOT fused.


There is no black ground wire to the ignition. If you are talking about a large black wire to the switch, this is the ACCESSORY feed to the fuse panel.

Here, download this 69 Dodge service manual. Yeah yeh, it's Dodge, but the Coronet wiring is the same as a Plymouth:

http://www.abodyjoe.com/pictures/Mis...e%20manual.pdf

The diagram you want is page 8-106

The drawing below is a crop from that page

Large RED no12 is power coming INTO the switch from the "in harness splice" in the ammeter circuit (J1-12R_

Large BLACK is hot in run and accessory and feeds power to the switched loads in the fuse panel (Q2-12BK)

YELLOW is the start wire going out through the bulkhead to the start relay (S2-18Y)

BROWN is the coil resistor bypass, or IGN2 goes out through the bulkhead to the coil + side of the ballast resistor (J3-14BR)

DARK BLUE is the "ignition run" circuit, or "IGN1" (J2-16DBL) which feeds power to the cluster gauges and warning lamps, and out through the bulkhead, feeds ignition system and regulator power

NONE OF this is fused, except via the fuse link, which as you have discovered, is poor protection.

383MAGNUMROADRUNNER

Sorry about the CAPS LOCK. I have done everything said already. I have a downloaded manual. Don't need to be scolded at my age. BYE BYE

440roadrunner

wowsorryimentioneditiguessyoushouldhaveitfixedthen right

lynchroad

Well,that must be a new way to say thanks to someone tryin to help !!!
Have not seen it before,but I sure NOT gonna use it.....

67hemidart

I think he eat to much Mopar electrical

MrOldart2U

I would bet the amp gauge was toast.... But thats all a W.A.G. and not needed now...